300B Tube Amps with 15/16 Watts Per Channel?

@atmasphere thanks for all the info. That’s helpful and appreciate taking the time to educate some of us. I don’t think the Cube drivers are horn loaded but they do have a whizzer cone. In EU they are typically paired with Tektron 211 PSET amps at shows and the sound is sublime. I have seen them powered with 3/4 watts 2A3 SET in small rooms but I don’t think that will work in my situation as my room is a open configuration with lot of volume. Have gone through some amps, like FW SIT3, Pass X25, LTA UL and some other Class D but in all cases it seemed to lack dynamics until I paired it with a LM 805IA. This integrated is also heavy modified and it sounded very good but the only issue is this amp is easily prone to noise and ground loop issues. So in my experience, this speaker needs some bit of power depending on the room situation. I am now trying to see where can I go next. I know for sure getting a Tektron PSET would be an end game for this speakers, so I am trying to explore other options like Otomon which apparently seems very nice as well.

@debjit_g  There is an old customer of mine who has a prototype pair of the design used for the Blackbird amps that Spatial audio is producing.  PP300b and they produce about 24 watts/ch.   He has one of the Cube speakers as I recall and the amps drive them with ease.  So I am sure a well designed and preferably fully balanced PP 300b would have no problem.  

Some of this fascinating discussion goes over my lumpy bald noggin and I’m not sure I’d want the news a phrenologist might report.  I have the Sachs/Olsen 300B mono blocks and thier Pre. No listening fatigue is my truest test and that’s an A+.  
 

@donsachs I have no doubt that a 24w/ch PP 300b is more than what I would need. I know Clayton's original Spatial Audio very well as I had their open baffle at sometime. The amp looks beautiful and would love to own them, however, its priced out of my current budget (I have other diy projects lined up on the digital side). On another point, I am not sure how important balanced/unbalanced in my system. I have gone through a plethora of DACs in the past couple of yrs and some do sound slightly better in balanced configuration vs unbalanced. The reason why I bring up DACs is because if you have a unbalanced source, I am not sure how beneficial having balanced downstream is. Moreover, in my system their isn't much difference between the two anyway, it more of splitting hairs and I don't run long interconnects.